1. Field of the Invention
The present invention relates generally to the field of bayonet mounts, and more particularly to an improved bayonet mount for quickly and releasably mounting a lens on a camera body.
2. Description of the Prior Art
Bayonet mounts are, of course well known, and have heretofore been specifically employed in the camera art to mount a lens on a camera body. Examples of such known forms of bayonet mounts are representatively shown in U.S. Pat. Nos. 2,618,201; 4,063,264; and 4,118,713.
Such known bayonet mounts have included a plurality of claws mounted on a marginal portion or a lens, for insertion into a camera body opening provided with a correspondingly plurality of claw-receiving slots or recesses. However, these earlier forms have, upon information and belief, generally contemplated that the claws and slots be of uniform height, width and spacing. While providing an operable bayonet mount, this configuration has permitted the lens to be inserted at any angular position at which the symmetrical claws would be aligned with the cooperative symmetrical slots. For example, if there were three claws spaced equally at nominal centerline angles of 120 degrees, the lens could be inserted at any of three angular positions.
To avoid this, it is also known to provide a nonsymmetrical tooth or tab and slot to positively require that the lens be in a predetermined angular position prior to insertion. Such structure is typically shown in the aforesaid U.S. Pat. No. 2,618,201. While this arrangement prevented the lens from being entirely attached in an incorrect angular orientation, it was still possible to insert some of the claws of a misaligned lens through some of the wrong slots. In such misaligned condition, part of the lens marginal portion could pass through the opening. This resulted in the lens being not fully inserted and tilted relative to the axis of the lens and body opening. In such a position, some of the claws have passed through the opening and some have not. The installer is therefore prevented from rotating the lens to its correct angular position for insertion without first withdrawing it fully from the body opening, and rotating it before attempting once again to insert it into the camera body opening.
In order to avoid the above mentioned problem, it is presently necessary that a lens have the correct angular alignment with the body opening before an attempt is made to insert it. Currently, many lens/body combinations have an index on the lens and a corresponding index on the body so that the installer may begin proper insertion of a lens by first aligning the indices. A refinement of this method is for the indices of the lens and body to be raised, or depressed, or identified in such a way that the installer can "feel" them and thus begin installation correctly by tactile means rather than visual means. (See, e.g., U.S. Pat. No. 2,618,201)